The public switched telephone network (PSTN) is a circuit-switched network that uses dedicated lines to communicate telephone calls. At a central office, a digital Class 5 switch receives analog telephone signals from a user, digitizes the analog telephone signals, and then multiplexes the digital signals over a network of circuit-switched backbone transport lines. An interexchange carrier (IXC) transports the call to a destination Local Access Transport Area (LATA), where it is handed to a local service provider and reconverted to an analog signal for delivery to a second user.
As the Internet has driven demand for greater bandwidth over data networks, new broadband technologies have emerged that allow the delivery of telephone calls using data packets communicated over broadband networks. Unfortunately, current solutions have been technology dependent, supporting only a single architecture.